P0021 - Camshaft Position 'B' - Timing Over-Advanced or System Performance (Bank 2)
Last updated:
System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P0021 is a generic OBD-II code indicating that the Engine Control Module (ECM) has detected the intake camshaft position for Bank 2 is more advanced than the commanded timing. This involves the Variable Valve Timing (VVT) system. The ECM monitors the camshaft position via the Camshaft Position (CMP) sensor and controls the angle by modulating oil pressure through a Variable Timing Solenoid (VTS). When the actual phase angle exceeds the target by a calibrated threshold (typically 5-10 degrees) for a specific duration, P0021 is stored. This system relies heavily on oil viscosity and pressure.
Possible Causes
Dirty engine oil or incorrect oil viscosity (clogged oil passages)
Faulty VVT/VCT solenoid (Oil Control Valve) on Bank 2
Failed camshaft phaser/actuator unit
Stretched timing chain or failed chain tensioner causing mechanical misalignment
Symptoms
Recommended Solution
- Check engine oil level and condition. Perform an oil and filter change if service is overdue or if incorrect oil is used.
- Use a scan tool to perform an active test on the VVT solenoid for Bank 2. Observe changes in engine RPM.
- Measure the solenoid's resistance (standard values usually between 7-12 Ohms depending on application).
- Inspect wiring and connectors for corrosion or heat damage. Clean connectors with contact spray.
- If the problem persists, remove the VVT solenoid to check for debris in the screen. Replace the solenoid or the camshaft phaser if mechanical internal failure is confirmed.
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
Do you also have
other fault codes?
See how P0021 connects with your other fault codes. Our advanced analysis tool identifies causal relationships and root causes directly.